Through Bolts in concrete Structures 7

[dik]

Is there a good article on the design of 'through bolts' in concrete structures? For example, a bolt going through a concrete wall or column supporting a steel beam.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JLNJ]

About 15 years ago I did something similar using Hilti's HSL anchors. They seemed like they were best suited for the job. This was either before ACI 318's Appendix D or when it was in its infancy. I maximized the bolt spacing vertically in the connection (extending it below the beam IIRC) and maximized cover to the column side edges knowing that the rebar would provide a healthy amount of confinement. Probably not totally by the book, but the book hadn't been written yet. Maybe it still hasn't for your application.

I know the local Hilti sales guy was happy because I required a whole bunch of these unusual bolts.

 

[sticksandtriangles]

The go to paper on anchor reinforcing in concrete says that you can ignore concrete pryout failures for embedments deeper than 12*Ø. As celt said, I think you can ignore this failure for through bolts if you meet this requirement.

https://www.sefindia.org/forum/file...nforcement_a_petrolium_project_papers_199.pdf

S&T -

http://www.re-tug.com

 

[dik]

Thanks... I was actually concerned about bearing of the through bolt on the concrete... likely not an issue.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[slickdeals]

Your load doesn't seem much. For tower crane tie backs, I have typically used pretensioned through bolts with a plate on each side. The load transfer mechanism is through preventing slip against the engaging surface (slab surface and soffit in my case) and then making sure slab has enough reinforcement to carry the load delivered to it. The reason to do this approach is because the building department doesn't like for movement inside a sleeved connection for a through bolt for tower crane. Has worked successfully. Not suggesting you go this route, but it's an option to consider.

 

[dik]

Thanks, slickdeals... I've decided to leave it to the EOR. I think I was overreacting.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[DoubleStud]

Is it possible to just treat it like Chapter 17 headed anchors?

 

[dik]

thanks Double... as the fox indicated, I looked at the capacity of it as a headed stud with a length equal to the column depth, assuming it could develop the necessary 'cone', and it had ample capacity. My only exception, and for the EOR to confirm, was that the contractor proposed six BAR 1/2x3x3 plate washers and I don't know if the EOR wants a solid plate on the backside.

I'm a lot happier now; when I first looked at the proposal by the contractor using HAS E-55s and found they only had less than half the capacity... through bolts have to be used... I've learned something... I've generally preferred chemical anchors to through bolts, and the concept is flawed. My SMath program treats it like a 'headed stud' for pull-out, and determines load capacity based on this as well as the strength in tension and shear for the 'through bolt' material itself.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JedClampett]

It's too bad there's not a "Through Bolt Association" that could sponsor research into this. Structural Engineers have been using through bolts from time immemorial, yet there is no textbook or code guidance (not anything I could find) on them.
I can find endless papers on fiber reinforcing, which is of dubious value, but nothing on something useful. But the difference is that fiber reinforcing has a value to those companies that sell them, but any old bolt can be made into a through bolt. The same with epoxy anchors, but once again, there's an industry that makes them. At least those have a value.

 

[dik]

Thanks Jed... I was surprised. I've always use Hilti HAS E-55s instead of through bolts because of lack of design information, but it appears they have half the capacity of a through bolt. Live and learn... I, initially, missed the analogy to headed studs that fox presented...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[HTURKAK]

MR. DIK,

I have looked this thread two days ago.. Apparently , there are some discrepancies for the approach to this problem in my zone..

If you say "Through Bolt " , the concrete element is drilled and a bolt having smaller dia. is inserted . That is, there is annular space btw bolt and the hole. This will increase the bearing stress terribly.


I will suggest,

- fill the annular space with epoxy to reduce the contact stress ,
- read the "8.2 Dowel action" of the following doc. to see Højlund-Rasmussen the plastic hinge formation concept.













Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[dik]

Thanks HTURKAK, I've already asked the EOR to confirm the space is filled, and I'll take a look at the document. I'm not too sure that filling the void has much of an effect. It's the tension that keeps the plate in place, and I think the analogy of a headed stud is close.

About 50 years back, I was involved in a court case (not mine) when ACI shear friction was just coming into play. The university prof that I was disagreeing with (his position was that shear friction didn't work) had run a finite element study on the dowel part of the shear friction embedment and ended up with concrete compressive stresses of approx 13ksi. He couldn't answer the question, "What happens if the concrete crushes, how are the forces redistributed?" Normally he was pretty good... he was one of the professional engineers that served as one of my referees for getting registered. There's a real interesting story behind that, but I won't bore you with the details... His FEM model prompted me to write my own 3D program,that I later used for work designing piezoelectric ceramic 'gas' bearings...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik